JP2016037249A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire having improved durability and damage-resistance of a side wall part.SOLUTION: A pneumatic tire includes a decoration part 7 which has a printed layer 8, and has an inner layer 9 and an outer layer 10 on an inside and an outside of the printed layer on a side wall part. Therein, when storage moduli at 25°C of the printed layer, the inner layer and the outer layer are respectively E1', E2' and E3', relations of E1'<E2' and E1'<E3' are satisfied, when storage moduli at 80°C of the printed layer, the inner layer and the outer layer are respectively E1', E2' and E3', and rates of change α1, α2 and α3 of high temperature storage moduli of the printed layer, the inner layer and the outer layer are respectively α1=|E1'-E1'|/E1', α2=|E2'-E2'|/E2' and α3=|E3'-E3'|/E3', relations of α1<α2 and α1<α3 are satisfied and, further, relations of E2'>E2' and E3'>E3' are satisfied.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a pneumatic tire.

  Conventionally, various pneumatic tires (hereinafter also simply referred to as tires) in which a decorative portion having an annular or other shaped printing layer is formed on the outer surface of the sidewall portion have been proposed (see, for example, Patent Document 1). .

JP 2013-237292 A

  Here, when the decorative portion having the printed layer as described above is provided on the tire, cracks may occur in the decorative portion due to distortion caused by the deformation of the tire during traveling, and thus the durability of the decorative portion is increased. It is demanded to improve. Moreover, when a tire contacts with a curb stone etc., a printing layer may peel off, Therefore It is calculated | required to improve the damage resistance of the decoration part which has a printing layer.

  Further, since tires are generally used even in severe environments such as high temperature environments, it is required to improve the durability and damage resistance of decorative parts even under such high temperature environments.

  The present invention has been made in view of the above problems, and provides a pneumatic tire that has improved durability and damage resistance of a decorative portion of a sidewall portion under a use environment including a high temperature environment. With the goal.

The gist configuration of the present invention is as follows.
The pneumatic tire of the present invention includes a decorative portion having a printed layer and an inner layer and an outer layer respectively disposed on the inner side and the outer side of the printed layer on the outer surface of the sidewall portion,
The storage elastic modulus of the printed layer when measured at a temperature of 25 ° C., the storage elastic modulus of the inner layer when measured at a temperature of 25 ° C., and the storage elastic modulus of the outer layer when measured at a temperature of 25 ° C. When E1 ₂₅ ′, E2 ₂₅ ′, and E3 ₂₅ ′, respectively,
E1 ₂₅ ′ <E2 ₂₅ ′ and E1 ₂₅ ′ <E3 ₂₅ ′
The filling,
The storage elastic modulus of the printed layer, the storage elastic modulus of the inner layer, and the storage elastic modulus of the outer layer when measured at a temperature of 80 ° C. are E1 ₈₀ ′, E2 ₈₀ ′, and E3 ₈₀ ′, respectively. The storage elastic modulus change rate α1, α2, α3 at high temperature of the printed layer, the inner layer, and the outer layer, respectively,
_{α1 = | E1 25 '-E1} 80' | / E1 25 ',
_{α2 = | E2 25 '-E2} 80' | / E2 25 ',
_{α3 = | E3 25 '-E3} 80' | / E3 25 ',
And the relational expression,
α1 <α2 and α1 <α3
And further, the relational expression,
E2 ₂₅ ′> E2 ₈₀ ′ and E3 ₂₅ ′> E3 ₈₀ ′
It is characterized by satisfying.
According to the pneumatic tire of the present invention, it is possible to improve the durability and the damage resistance of the decorative portion of the sidewall portion under a use environment including a high temperature environment.
The “storage elastic modulus” refers to a value measured according to JIS K7244.

Here, in the pneumatic tire of the present invention, when the thickness of the printing layer is d1, the thickness of the inner layer is d2, and the thickness of the outer layer is d3,
d1> d2 and d1> d3
It is preferable to satisfy.
By satisfying this relational expression, it is possible to further improve the durability of the decorative part in a use environment including a high temperature environment.
In the present specification, the “layer thickness” refers to the thickness of each layer at the maximum thickness position, and is measured by mounting a tire on an applicable rim, filling a specified internal pressure, and no load. Shall. Here, “applicable rim” is an industrial standard effective in the area where tires are produced and used. In Japan, JATMA (Japan Automobile Tire Association) JATMA YEAR BOOK, and in Europe, ETRTO (The European Tire and RIM Technical Organization's STANDARDDS MANUAL, TRA (The Tile and Rim Association, Inc.) YEAR BOOK OK, etc. Design Rim). The “specified internal pressure” refers to an air pressure corresponding to the maximum load capacity in the applicable size / ply rating described in the above JATMA YEAR BOOK and the like.

Further, in the pneumatic tire of the present invention, the thickness of the printed layer, the thickness of the inner layer, the thickness of the outer layer, and the total thickness of the printed layer, the inner layer and the outer layer, When d1, d2, d3, and d4, respectively,
1/2 ≦ d1 / d4 ≦ 4/5
It is preferable to satisfy.
By satisfy | filling said relational expression, the durability and damage resistance of a decoration part in the use environment containing a high temperature environment can be improved further.

  ADVANTAGE OF THE INVENTION According to this invention, the pneumatic tire which improved the durability and the damage resistance of the decoration part of a sidewall part in the use environment containing a high temperature environment can be provided.

It is a tire width direction sectional view of a pneumatic tire concerning one embodiment of the present invention. 1 is a side view of a tire / rim assembly in which a pneumatic tire according to an embodiment of the present invention is assembled to a rim. It is a fragmentary sectional view which shows a decoration part and a side wall part roughly.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a tire width direction sectional view of a pneumatic tire according to an embodiment of the present invention. In FIG. 1, only one half of the tire width direction with the tire equatorial plane CL as a boundary is illustrated, but the other half of the tire width direction (not shown) has the same configuration. As shown in FIG. 1, the pneumatic tire 1 includes an annular tread portion 2 that is continuous in the tire circumferential direction and a pair (in FIG. 1) that extends inward in the tire radial direction continuously to both sides of the tread portion 2. The side wall part 3 of only one side is shown, and a pair of bead parts 4 (only one side is shown in FIG. 1) connected to the inner side of the side wall part 3 in the tire radial direction. Here, the internal structure of the tire is not particularly limited, but in the example shown in FIG. 1, the tire 1 is a pair of bead cores 4 a (only one side is shown in FIG. 1) embedded in the bead portion 4. In this example, a belt 6 composed of two belt layers is provided on the outer side in the tire radial direction of the carcass 5 straddling the toroidal shape.

FIG. 2 is a side view of a tire / rim assembly in which a pneumatic tire according to an embodiment of the present invention is assembled to an applied rim. As shown in FIG. 2, the tire 1 is assembled to the application rim R and includes an annular decorative portion 7 on the outer surface 3 a of the sidewall portion 3. In the illustrated example, marks M <b> 1 and M <b> 2 made of alphabets are attached to two places on the circumference of the decorative portion 7.
Next, FIG. 3 is a partial sectional view schematically showing the decorative portion 7 and the sidewall portion 3. As shown in FIG. 3, the decorative portion 7 includes a printed layer 8 and an inner layer 9 and an outer layer 10 disposed on the inner side and the outer side of the printed layer 8, respectively.

  Here, in this embodiment, the printing layer 8 is formed by applying a paint such as ink to the outer surface 3a of the sidewall portion 3 by, for example, screen printing, inkjet printing, letterpress printing, or other printing. It is.

  The printing layer 8 can be composed of a laminated structure of a white paint layer and a colored paint layer (color other than white) outside the tire. The layer is preferably thicker than the colored paint layer. Such a laminated structure can be applied to all or part of the circumference of the printing layer 8. The colored paint layer may be laminated directly on the surface of the white paint layer, or may be formed via a primer layer. On the other hand, the printing layer 8 can also be composed of only a colored paint layer (a color other than white). In this case, the inner layer 9 is preferably white in order to ensure color developability.

Here, in the present invention, the material of the printing layer 8 is not particularly limited. For example, an oligomer, a monomer, and a colorant are main components. If necessary, a photopolymerization initiator, an ultraviolet absorber, an oxidation agent are used. An active energy ray-curable ink in which an inhibitor, a light stabilizer, an adhesion promoter, a rheology modifier, a dispersant and the like are blended can be used. The storage elastic modulus E1 ₂₅ ′ and E1 ₈₀ ′ of the printing layer 8 can be controlled within a predetermined range by adjusting the blending amount of the above materials. More specifically, as a material for the printing layer 8, UF-245 ink series manufactured by DNP Fine Chemical Co., etc. can be used. Furthermore, the material of the inner layer 9 and the outer layer 10 is not particularly limited, but includes, for example, an oligomer and a monomer as main components, and if necessary, a photopolymerization initiator, an ultraviolet absorber, an antioxidant, and a light stabilizer. An active energy ray-curable ink for forming an intermediate layer in which an agent, an adhesion promoter, a rheology modifier and the like are blended can be used. Further, the storage elastic moduli E2 ₂₅ ′, E2 ₈₀ ′, E3 ₂₅ ′, and E3 ₈₀ ′ of the inner layer 9 and the outer layer 10 can be controlled within a predetermined range by adjusting the blending amounts of the above materials. . More specifically, as a material for the inner layer 9 and the outer layer 10, a UF-64 ink series manufactured by DNP Fine Chemical Co., etc. can be used. As the active energy rays, α rays, γ rays, X rays, ultraviolet rays, electron beams and the like can be used.

  Moreover, in this embodiment, in order to make the printing layer 8 visible, at least the outer layer 10 outside the tire among the inner layer 9 and the outer layer 10 is a transparent layer.

The pneumatic tire of this embodiment was measured at a storage elastic modulus of the printed layer 8 when measured at a temperature of 25 ° C., a storage elastic modulus of the inner layer 9 when measured at a temperature of 25 ° C., and a temperature of 25 ° C. When the storage elastic modulus of the outer layer 10 is E1 ₂₅ ′, E2 ₂₅ ′, and E3 ₂₅ ′, respectively,
E1 ₂₅ ′ <E2 ₂₅ ′ and E1 ₂₅ ′ <E3 ₂₅ ′
Meet.
Further, the storage elastic modulus of the printed layer 8, the storage elastic modulus of the inner layer 9, and the storage elastic modulus of the outer layer 10 when measured at a temperature of 80 ° C. are respectively E1 ₈₀ ′, E2 ₈₀ ′, and E3 ₈₀ ′. And the storage elastic modulus change rates α1, α2, α3 at high temperatures of the printed layer 8, the inner layer 9, and the outer layer 10, respectively,
_{α1 = | E1 25 '-E1} 80' | / E1 25 ',
_{α2 = | E2 25 '-E2} 80' | / E2 25 ',
_{α3 = | E3 25 '-E3} 80' | / E3 25 ',
When the pneumatic tire of this embodiment,
α1 <α2 and α1 <α3
And further, the relational expression,
E2 ₂₅ ′> E2 ₈₀ ′ and E3 ₂₅ ′> E3 ₈₀ ′
Meet.
Hereinafter, the effect of the pneumatic tire of this embodiment is explained.

According to the pneumatic tire of this embodiment, first, the printed layer 8 having a low storage elastic modulus when measured at a temperature of 25 ° C., the inner layer 9 and the outer layer having a high storage elastic modulus when measured at a temperature of 25 ° C. 10, the printed layer 8 absorbs distortion at the time of tire deformation and improves the durability of the decorative portion 7, while the inner layer 9 and the outer layer 10 prevent damage to the decorative portion 7. Can be improved. In particular, since the printing layer 8 has a relatively small change rate α1 of the storage elastic modulus at a high temperature with respect to a room temperature, the temperature dependency provides an effect of absorbing strain at the time of tire deformation even in a high temperature environment. In addition, the inner layer 9 and the outer layer 10 have relatively high storage elastic modulus change rates α2 and α2 at a high temperature with respect to room temperature, and the storage elastic modulus decreases. Under the environment, the rigidity step between the respective layers can be relaxed, the durability of the decorative portion 7 can be ensured, and the adhesion to the tire can also be ensured.
Therefore, according to the pneumatic tire of this embodiment, the durability and the damage resistance of the decorative portion of the sidewall portion can be improved under a use environment including a high temperature environment.

  Here, in the present invention, the inner layer 9 and the outer layer 10 are preferably made of the same material. For example, when the inner layer 9 and the outer layer 10 are formed in a wider range than the formation range of the printing layer 8, the adhesion between the edge of the inner layer 9 and the edge of the outer layer 10 becomes good, This is because the durability and the damage resistance of the decorative portion 7 of the sidewall portion 3 can be further improved, and are also preferable from the viewpoint of productivity and cost.

In the pneumatic tire of the present invention, the relational expression,
E2 ₂₅ ′ / E1 ₂₅ ′ ≦ 7.1 and E3 ₂₅ ′ / E1 ₂₅ ′ ≦ 7.1
It is preferable to satisfy.
By satisfying the above numerical range, it is possible to improve the durability of the decorative portion 7 so that the rigidity step between the printed layer 8 and the inner layer 9 and the outer layer 10 does not become too large.

Furthermore, in the pneumatic tire of the present invention, the outer layer 10 when the decorative portion 7 is measured on the outer side of the outer layer 10 on the outer side of the tire at a temperature of 25 ° C. is the storage elastic modulus E4 ₂₅ ′ when measured at a temperature of 25 ° C. It is preferable to further have a protective layer larger than the storage elastic modulus E3 ₂₅ ′. Thereby, the damage resistance of the decorative portion 7 can be further improved. Here, the material for the protective layer is not particularly limited. For example, a (meth) acrylic acid resin or a resin obtained by modifying this resin with silicone can be used, and in addition to these resins, a urethane-based material can be used. A resin or a resin mixed with a carbonate-modified resin of this resin can also be used. Here, the storage elastic modulus E4 ₂₅ ′ of the protective layer can be controlled within a predetermined range by adjusting the blending amount of the above materials. More specifically, as a material for the protective layer, a (meth) acrylic acid-based resin or a resin obtained by modifying this resin with silicone includes “OP-SA13”, “OP-SA79”, “OP-” manufactured by DNP Fine Chemical Co., Ltd. Examples of “SA355”, “OP-SA356”, urethane resin, or resin obtained by carbonate modification of this resin include “OP-U354” manufactured by DNP Fine Chemical Co., Ltd.

Specifically, from the viewpoint of ensuring durability with the printing layer 8 having a low storage elastic modulus while improving the damage resistance with a protective layer having a high storage elastic modulus, the storage elastic modulus E1 ₂₅ ′ of the printing layer 8 is It is preferable to be 4.0 × 10 ⁶ (Pa) or less, and the storage elastic modulus E4 ₂₅ ′ of the protective layer is preferably 1.0 × 10 ⁷ (Pa) or more.
On the other hand, from the viewpoint of ensuring the durability of the decorative portion 7 by making the rigidity step in the decorative portion 7 not too large, the storage elastic modulus E1 ₂₅ ′ of the printed layer 8 is 5.0 × 10. ⁵ (Pa) or more is preferable, and the storage elastic modulus E4 ₂₅ ′ of the protective layer is preferably 5.0 × 10 ⁸ (Pa) or less.

In the pneumatic tire of the present invention, when the storage elastic modulus of the side rubber (rubber constituting the sidewall portion 3) adjacent to the inside of the decorative portion 7 when measured at a temperature of 25 ° C. is E5 ₂₅ ′. ,Relational expression,
E1 ₂₅ ′ <E5 ₂₅ ′
Preferably satisfying
E2 ₂₅ ′ <E5 ₂₅ ′ and E3 ₂₅ ′ <E5 ₂₅ ′
It is further preferable to satisfy
When the above relational expression is satisfied, the printed layer 8, the inner layer 9, and the outer layer 10 can follow the strain of the side rubber particularly when the sidewall portion 3 of the tire is deformed. This is because the durability of the decorative portion 7 can be further improved.

Here, in the pneumatic tire of the present invention, when the thickness of the printed layer 8 is d1, the thickness of the inner layer 9 is d2, and the thickness of the outer layer 10 is d3,
d1> d2 and d1> d3
It is preferable to satisfy.
This is because by increasing the thickness of the soft layer having a low storage elastic modulus, it becomes easier to follow the strain caused by the deformation of the tire, and the durability of the decorative portion 7 can be further improved.

In the pneumatic tire of the present invention, the thickness of the printing layer 8, the thickness of the inner layer 9, the thickness of the outer layer 10, and the total thickness of the printing layer 8, the inner layer 9, and the outer layer 10. Are d1, d2, d3, and d4, respectively,
1/2 ≦ d1 / d4 ≦ 4/5
It is preferable to satisfy.
When the ratio d1 / d4 is ½ or more, the storage elastic modulus is low and the soft layer is thickened so that it can more easily follow the distortion caused by the deformation of the tire, and the durability of the decorative portion 7 can be further improved. On the other hand, by setting the ratio d1 / d4 to 4/5 or less, the relative thickness of the inner layer 9 and the outer layer 10 can be ensured, and the damage resistance of the decorative portion 7 can be further improved. Because it can.

  Specifically, in order to make the durability of the decorative portion 7 and the damage resistance more compatible, the thickness d1 of the printing layer 8 is preferably 40 μm or less, and the thickness d2 of the inner layer 9 and the outer layer The thickness d3 of 10 is preferably 10 to 20 μm.

In the pneumatic tire of the present invention, the concealment rate of the inner layer 9 and the outer layer 10 is preferably smaller than the concealment rate of the printing layer 8.
This is because by reducing the concealment ratio of the inner layer 9 and the outer layer 10, it is possible to form a catch due to microscopic unevenness and further improve the adhesiveness. Further, when the concealment rate is low, a region where the paint is not applied microscopically is formed, so that the distortion can be released and the durability of the decorative portion 7 can be further improved. Here, the “hiding ratio” means the paint area per unit area of the tire surface, and is obtained by performing image processing using a microscope, for example, and measuring the area where the paint is applied. Can do.
That is, while the inner layer 9 and the outer layer 10 are formed in a wider range than the formation range of the printing layer 8, when viewed microscopically in a certain unit area of the sidewall portion 3, the coating area is the printing layer. It is preferably less than 8 paint areas.

  In order to confirm the effect of the present invention, a tire according to Invention Examples 1 to 6 and a tire according to Comparative Example 1 were prototyped, and a test for evaluating durability and damage resistance of the decorative portion was performed. Each of the tires has a common internal structure as shown in FIG. 1 and includes a decorative portion having a printed layer, an inner layer, and an outer layer on the outer surface of the sidewall portion. The specifications of each tire are shown in Table 1 below, and the specifications not shown in Table 1 are common to each tire.

<Durability of decorative parts>
Each of the above tires was incorporated into an applicable rim, filled with a specified internal pressure, and mounted on the vehicle. And the test which measures the crack extension length which generate | occur | produces in a decoration part after driving | running | working 20,000 km with a real vehicle was done, and durability of the decoration part was evaluated. The evaluation is expressed as an index when the tire according to Comparative Example 1 is set to 100, and the larger the value, the better the durability of the decorative portion.

<Trade resistance of decorative parts>
About each said tire, the test which scratches a decoration part under a load condition of 1200 g with a coin was done, and the damage resistance of the decoration part was evaluated. The evaluation is expressed as an index when the tire according to Comparative Example 1 is set to 100, and the larger the value, the better the damage resistance of the decorative portion.
These evaluation results are shown in Table 1 below.

  As shown in Table 1, it can be seen that the tires according to Invention Examples 1 to 6 are superior in the durability of the decorative portion and the damage resistance as compared with the tire according to Comparative Example 1. Moreover, it can be seen from comparison between Invention Example 1 and Invention Example 2 that Invention Example 1 satisfying the relational expressions d1> d2 and d1> d3 is excellent in durability of the decorative portion 7. Further, by comparing Invention Example 1 and Invention Examples 3 to 6, Invention Examples 1, 4, and 5 satisfying the relational expression, 1/2 ≦ d1 / d4 ≦ 4/5 are more decorative than Invention Examples 3 and 6. It can be seen that the durability and the damage resistance of the portion 7 are excellent.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Side wall part 4 Bead part 4a Bead core 5 Carcass 6 Belt 7 Decoration part 8 Print layer 9 Inner layer 10 Outer layer

Claims (3)

Provided on the outer surface of the sidewall portion is a decorative portion having a printed layer and an inner layer and an outer layer disposed on the inside and outside of the tire of the printed layer, respectively.
The storage elastic modulus of the printed layer when measured at a temperature of 25 ° C., the storage elastic modulus of the inner layer when measured at a temperature of 25 ° C., and the storage elastic modulus of the outer layer when measured at a temperature of 25 ° C. When E1 ₂₅ ′, E2 ₂₅ ′, and E3 ₂₅ ′, respectively,
E1 ₂₅ ′ <E2 ₂₅ ′ and E1 ₂₅ ′ <E3 ₂₅ ′
The filling,
The storage elastic modulus of the printed layer, the storage elastic modulus of the inner layer, and the storage elastic modulus of the outer layer when measured at a temperature of 80 ° C. are E1 ₈₀ ′, E2 ₈₀ ′, and E3 ₈₀ ′, respectively. The storage elastic modulus change rate α1, α2, α3 at high temperature of the printed layer, the inner layer, and the outer layer, respectively,
_{α1 = | E1 25 '-E1} 80' | / E1 25 ',
_{α2 = | E2 25 '-E2} 80' | / E2 25 ',
_{α3 = | E3 25 '-E3} 80' | / E3 25 ',
And the relational expression,
α1 <α2 and α1 <α3
And further, the relational expression,
E2 ₂₅ ′> E2 ₈₀ ′ and E3 ₂₅ ′> E3 ₈₀ ′
A pneumatic tire characterized by satisfying When the thickness of the printed layer is d1, the thickness of the inner layer is d2, and the thickness of the outer layer is d3,
d1> d2 and d1> d3
The pneumatic tire according to claim 1, wherein: The thickness of the printed layer, the thickness of the inner layer, the thickness of the outer layer, and the total thickness of the printed layer, the inner layer, and the outer layer are d1, d2, d3, and d4, respectively. When the relational expression,
1/2 ≦ d1 / d4 ≦ 4/5
The pneumatic tire according to claim 1 or 2, satisfying

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